The mental health concerns of children and the identification of risk factors responsible for childhood psychopathology are a high research priority for the NIMH as reflected in the NIMH "National Plan for Research on Child and Adolescent Mental Disorders." A parallel concern of the research community is that psychiatric health issues are understudied in females, especially for disorders that are more prevalent among males. This is true for Attention Deficit Hyperactivity Disorder (ADHD). Because family disruption and severe behavioral disturbances are observed less frequently among ADHD girls in comparison to ADHD boys, they are less likely than boys to come to the attention of health care providers and are rarely enrolled in research protocols. When they are, their numbers are often insufficient to make meaningful inferences. The under-identification and under-treatment of ADHD girls may have substantial mental health and educational implications. Thus, research is needed to develop a better understanding of ADHD in girls. In our pilot study of girls with DSM-III Attention Deficit Disorder (ADD) we demonstrated the feasibility of studying this disorder in females. We now propose to extend this research to a family genetic study of DSM-III-R ADHD in girls. This will complement our studies of boys with DSM-III-R ADHD. We already have shown that, among boys, ADHD is familial and that the familial correlates of psychiatric comorbidity shed light on the etiologic relationships between ADHD and conduct, anxiety and major depressive disorders. We have completed the ascertainment of boys with ADHD and a contrast group of 120 normal control boys of similar age, social class, and ethnic background. We collected cognitive, social functioning and psychiatric diagnostic data as well as measures of environmental adversity from these probands, the 454 parents and siblings of ADHD probands and the 368 parents and siblings of normal controls. We are currently following these boys and their siblings over a five year period to assess family-genetic, psychosocial and cognitive predictors of outcome in ADHD. The overall goal of the proposed research is to determine if our findings among ADHD boys will generalize to a sample of ADHD girls. We also seek t determine if there are gender differences in the family- genetic correlates of ADHD and if the disorder is expressed differently in boys and girls. To achieve our goals we will, in the five years proposed for this study, ascertain and assess 140 girl probands with ADHD, and 120 girl controls. Although more work is needed to comprehensively understand ADHD in boys, we believe that now is the right time to pursue a study of ADHD girls. Our preliminary studies of ADD girls demonstrate the feasibility of finding girl patients and provide data on which to base our initial hypotheses. Our work with boys provides additional directions and hypotheses. By initiating a family study of ADHD girls, we intend to lay the groundwork for a long-term longitudinal study of the girls and their families. This, in conjunction with our longitudinal family study of ADHD boys, should provide the field with valuable data about ADHD in the years to come.